Results from the APEX Experiments at Fermilab


Published Results from the APEX Test Experiment (T861)

The T861 experiment placed lower limits on the decay rate of antiprotons into five different two-body decay modes. These limits are listed in the current particle data book. Results from the T861 test experiment are published in S. Geer et al; Phys. Rev. Lett. 72, 1596 (1994).
Antiproton -> electron + photon....Lifetime/BR > 1848 years (95% CL)
Antiproton -> electron + pi0.......Lifetime/BR >  554 years (95% CL)
Antiproton -> electron + eta.......Lifetime/BR >  171 years (95% CL)
Antiproton -> electron + K0 short..Lifetime/BR >   29 years (95% CL)
Antiproton -> electron + K0 long...Lifetime/BR >    9 years (95% CL)

Published Results from the APEX Experiment (E868)

The APEX experiment was designed to search for all possible two-body Antiproton decay modes with an electron in the final state. In addition, as an R&D project, a limited acceptance muon telescope was installed in the APEX experiment to make an exploratory search for decay modes with a muon in the final state. The goal of the APEX experiment is to improve on the sensitivity of the T861 results (APEX test experiment) by about a factor of 1000.

Limits on Antiproton -> muon + X

The E868 experiment has placed limits on 6 antiproton decay modes with a muon in the final state, described in:
hep-ex/9807025, Phys.Rev. D58, 111101, (1998).
Antiproton -> muon + photon.....Lifetime/BR > 50000 years (90% CL)
Antiproton -> muon + pi0........Lifetime/BR > 48000 years (90% CL)
Antiproton -> muon + eta........Lifetime/BR >  7900 years (90% CL)
Antiproton -> muon + K0 short...Lifetime/BR >  4300 years (90% CL)
Antiproton -> muon + K0 long....Lifetime/BR >  6500 years (90% CL)
Antiproton -> muon+gamma+gamma..Lifetime/BR > 23000 years (90% CL)

Limits on Antiproton -> electron + X

The E868 experiment has placed limits on 7 antiproton decay modes with an electron in the final state, described in:
hep-ex/9908036, Phys. Rev. D62, 052004, (2000), hep-ex/9910013, Phys.Rev.Lett. 84, 590, (2000).
Antiproton -> electron + photon.....Lifetime/BR > 700000 years (90% CL)
Antiproton -> electron + pi0........Lifetime/BR > 400000 years (90% CL)
Antiproton -> electron + eta........Lifetime/BR >  30000 years (90% CL)
Antiproton -> electron + K0 short...Lifetime/BR >    300 years (90% CL)
Antiproton -> electron + K0 long....Lifetime/BR >  10000 years (90% CL)
Antiproton -> electron + omega......Lifetime/BR >    100 years (90% CL)
Antiproton -> electron+gamma+gamma..Lifetime/BR >  20000 years (90% CL)